Embarassed to ask such an basic question but, how do I get the wiper blades off my '73 to change them? They must be rusted or stuck or I just don't know what I'm doing. But, I don't want to force them and break something.
The original style wiper blades (as well as most "direct replacements") have a small release button or tab near the center. Simply push down on that button/tab while pulling the blade up off the pivot pin on the wiper arm.
Some "universal fit" replacement blades are a bit more complicated. They have a plastic tang that snaps into the groove in the wiper arm pivot pin (similar to the style described above). But they lack a release tab so you have to pry down on the plastic retainer tang with a small screwdriver.
Other "universal fit" blades have a plastic "adapter" piece that snaps down into the center of the blade assembly. It snaps down over the pivot pin and latches the blade in place. To remove these, you have to pry that plastic adapter piece up off the wiper arm pivot pin.